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Identity (NIP-06 / NIP-49)

Summary. Each wallet has a Nostr keypair that is its payment identity. The secret key is stored encrypted at rest (NIP-49 ncryptsec, owner-only file permissions). Crucially, this key is separate from your Grin seed, so you can rotate your identity to stay unlinkable without ever touching your funds.

Motivation

Two design tensions shape Goblin’s identity:

  1. Linkability. If your payment identity were derived from your wallet seed, it would be permanent: every payment forever tied to one key. Goblin wants you to be able to start fresh. So the nostr key is independent and rotatable.
  2. Safety at rest. The secret key sits on a phone. It must never be on disk in the clear, and the file must not be world-readable.

How it works

Your identity lives in wallet_data/nostr/identity.json, written with Unix mode 0600 inside a 0700 directory. Inside, the secret key is a NIP-49 ncryptsec: a bech32 blob encrypted with your wallet password via scrypt (work factor log_N = 16, ~64 MiB, interactive grade). The file also stores your npub in the clear (so the UI can show “you” before you’ve unlocked), your nip05 name if you’ve claimed one, an anonymous flag, and prev_npubs, a history of keys you’ve rotated away from.

There are three ways an identity comes to exist (IdentitySource):

  • Random (default): a brand-new independent key (Keys::generate). Unlinkable to your seed and to any other wallet.
  • Imported: you paste an nsec or restore an encrypted backup file, adopting an existing identity (name and history included).
  • Derived: a NIP-06 seed-derived key. Kept for legacy wallets; new wallets use Random.

Rotation generates (or imports) a new key, releases your old name from the authority, records the old npub in prev_npubs, and restarts the relay service under the new key, all without re-seeding, so your Grin balance is untouched.

Screenshot: Settings → Identity card (Copy npub, Back up to a file, Rotate nostr key, Import identity), dark theme.

Backup & restore. “Back up to a file” exports the whole identity (encrypted key + name + history) as one sealed JSON file. Importing it on a new device decrypts with the export-time password and re-encrypts under the new wallet’s password, so moving devices preserves your username and history. (Moving a wallet needs both backups: the seed phrase for funds, and the identity file for your name + key.)

Reference

  • IdentitySource enum and the NostrIdentity struct: goblin/src/nostr/identity.rs. Fields: ncryptsec, npub, nip05, anonymous, prev_npubs.
  • Encryption at rest: NIP-49 ncryptsec, scrypt NCRYPTSEC_LOG_N = 16.
  • File safety: write_private() (Unix 0600), restrict_dir() (0700); stored at wallet_data/nostr/identity.json.
  • Key derivation for the legacy Derived source: derive_keys() (NIP-06 BIP-44 path).
  • Rotation/import/backup UI: RotateState / ImportState / BackupState flows in goblin/src/gui/views/goblin/mod.rs; onboarding import in onboarding.rs (OnbImport).

References